Isomerization of hydrocarbons



Patented Doe. I 9, 19 41 Es PAT'E i zacs'svo' 151 OFFICE'rsonmarz'a'rron or mitocmons 4 George Cornelia Adriaan Schuit,Amsterdam, Netherlandsassignor to Shell Development Company, SanFrancisc of Delaware 0, Calm, a corporation No Drawing. Application July31, 1939, Serial No. I

287,621 In the Netherlands August 9, 1938- r 9 Claims. (Cl. 260-676)Thepresent invention relates to the catalytic isomerization ofhydrocarbons. More particularly, the invention relates to the catalyticconversion of normal or slightly branched saturated hydrocarbonscontaining. at least five carbon atoms to commercially, valuable more,highly branched isomers. Most particularly, the invention relates to apractical and economical process for the production of isopentane fromnormal pentane by catalytic isomerization.

As is well known, the various saturated hydrocarbons having at leastfourcarbon atoms can exist in a numberoi various isomeric modifications.Thus, the paraflinic hydrocarbons from pentane to dodecane can exist inthe following number of isomeric forms: Q

Pentane--- 3 Hexane" Heptane 9 Octane .18 Nonane 35 Decane 159 Undecane355 Dodecane -'802 Notwithstanding the large number of isomericmodification generally possible, these hydrocarbons, as found innatural-sources such as petroleum, occur almost exclusively in thenormal or I slightly branched modifications.

Although a few of the lower saturated aliphatic hydrocarbons, such aspentane in particular; are

used to a certain extent in organic syntheses, etc.,

by far the most important application of. these hydrocarbons, having atleast five carbon atoms,

is in fuels for internal combustion engines. Studies 01' the chemicalproperties and ignition characteristics of a variety of the numerouspossible isomers have shown that certain isomeric modifications arevastly superior to' others for this curring isomers are the leastpreferred. Normal pentane, for example, is obtained in large quantitlesfrom petroleum. It is chemically quite tin reactive and, in view. of itsvery poor ignition 40. purpose and that, in general, the naturallyoccharacteristics, is a poor fuel for internal combustion engines.pentane, on the other hand, is much more chem- The branchedmodification, iso-" ically reactive and may be readily condensed witholefinic hydrocarbons by an alkylation proces to produce saturatedhigher molecular weight hydrocarbons having excellent ignitioncharacterlstics. Isopentane is, furthermore, a valuable iuel componentper so, especially for aviation fuels. It has a high "antiknock rating"(89 vs. 61

tion in the suitability of various isomers for internal combustionengine fuels and the" relation For lack of a better term, this betweenbranchedness and ignition characteristics, is illustrated in thefollowing table:

' Table I I Critical Branchod- Compound Wrath 3 13% v ll'ormal heptane2/7 3 Triethyl methane- 3f! 4 2, l-dimethyl pentanom- 4/1 6 2, 2,3-trimethyl butanm... .1 6/7 13 In view of the vastly superiorproperties 1- isopentane over normal pentane and, in general,hydrocarbons of high branchedness over-hydrocarbons of low branchedness,it is apparent that a commercially practical process for the conversion015 normal pentane to isopentane andfor treating the large availablequantities of less desirable hydrocarbons of low branchedness toincrease their branchedness, is very desirable and valuable. .1

.It has long been known that certain acid-acting metal halides, such ascatalysts of the Friedel- Craft type in particular, exert a strongcatalytic influence on hydrocarbonxreactions. Aluminum chloride, forexample, is one of the most poweriul cracking and polymerizing catalystsknown and is widely used'in the cracking of petroleum hydrocarbons intolow boiling hydrocarbons and ,the polymerization of olefins to syntheticlubri-- cating oils. These catalysts, besides tending to catalyze therupture of. (2-0 and 0-H bonds,

when used under certain conditions, alsotend to Although it catalyzehydrocarbon isomerization. has long been known that certain saturatedhydrocarbons such as normal heptane and normal octane, when treatedunder certain conditions in 1 the presenceof aluminum chloride, areisomerized to a' certain extent to branched chainisomers, nocommercially practical methodior etfecting such isomerization has beendeveloped. At ordinary temperatures the rate of isomerization is tooslow to be commercially practical. At higher temperatures the rate ofisomerization is more favorable, but in the presence of these catalyststhe tendency for the hydrocarbons to under- Exempt: I

100 gram portions of normal pentane, 45 grams of aluminum chloride andgrams of hydrogen chloride were charged into an iron bomb and the bombmaintained at various constant temperatures for three hours. Thepercentages of normal pentane converted to lighter cracked prodizationof normal pentane and higher saturated hydrocarbons since, althoughthese hydrocarbons, in general, undergo isomerization more readily, theyare much more susceptible to cracking and decomposition reactions in thepresence of isomerization catalysts.

The process of this invention comprises isomerizing the hydrocarbon ormixture of hydrocfirbons to be treated with the aid of an acida tingmetal halide in the presence of a hydrogen halide and a metal which actscatalytically to inhibit decomposition and other side reactions.

The process of the invention isgenerally applicable to theisomerizationof saturated hydrocarbons containing at least five carbonatoms such as, for example, pentane, hexane, heptane, octane, nonane,decane, undecane, dodecane,

' cyclohexane, dimethyl cyclohexane, ethyl cycloucts and to isopentaneat the various temperaan object ofthe invention is to provide a morepractical and economical process for catalytically isomerizing saturatedhydrocarbons containing at least flve' carbon atoms to increase thebranchedness thereof. A more particular obiect is to provide a morepractical, and econom ical process for the catalytic conversion of nor-.mal saturated aliphatic hydrocarbons having irom 5 to about 12 carbonatoms to corresponding branched chain isomers. A still more particularobject is to provide aprocess for the economical production ofisopentane from normal pentane by catalytic isomerization. Other'obiects of the invention are to provide a catalytic isomerizationprocess wherein cracking, polymerization and other undesirable reactionsare effectively inhibited; to provide-a catalytic isomeriza-' tionprocess wherein elevated temperatures aiiording faster reactionrates'may be employed; and ,to provide a catalytic isomerization processwherein the practical catalytic life of the catalyst is materiallyincreased,

In copending application No. 284,753 filed July 15, 1939 there isdescribed an improved process whereby normal butane may be economicallyisomerized to isobutane while decomposition reactions are effectivelyinhibited. It is pointed out in the above-mentioned application thatnormal butane differs considerably from its higher homologues in thatitis considerably less reactive and,

-consequently, requires the use of higher tem- Deratures-in order ,toeffect the isomerization at a' practical and economical rate. I havefound that a process quite similar to that of the above-mentionedapplication is effective and most advantageous when applied to theisomer- 7 mixture of one .or more hydrocarbons.

hexane, and the like. Of these the paraflinic hydrocarbons containingfrom 5 to about 12 carbon atoms, and especially normal pentane. arepreferred. Normal hydrocarbons containing sixor more carbon atoms whentreated according to the process of the invention are isomerized to thecorresponding branched and multibranched chain isomers. Thus, forexample, normal hexane is isomerized to 2-methyl pentane and to dimethylbutane. The process can also be 'employed, if desired. to increase thebranchedness of branched: chain hydrocarbons when such further branchingis structurally possible. 2- methyl pentane, for example, maybetisomerized to dimethyl butane.

The hydrocarbon treated need not necessarily be a pure individualhydrocarbon but may be a Thus, the invention provides a practicalprocess for converting to isopentane the normal pentane content ofcommercialhydrocarbon mixtures such as are obtained from natural gases,petroleum distillates and from cracking of high molecular weighthydrocarbons. Conveniently treated normal pentane-containing mixtures.are the socalled amylene-pe'ntan fractions from which the oleflns havebeen substantially removed. Treatment of such mixtures which contain acertain amount of isopentane. results in very materially increasingtheir isopentane content and enhancing their value as raw materials inthe production of isopentene, alkylation products, etc. Technicalpentane fractions, such as those containing from to 98% normalpentaneandfrom' I without appreciable loss of pentanes due to decomposition andwhile' realizing a maximum active life of the catalyst employed. Othermixturesof saturated hydrocarbons such as cuts of .straight run gasolinewhich may or may not contain pentane, may also be advantageously treatedto produce mixtures of more highly branched saturated hydrocarbons whichare more suitable for alkylation with ethylene etc. and have superiorignition characteristics. The hydrocarbon or mixture of hydrocarbonstreated is, however, preferably substantially free of materials whichare polymerized by the isomerization catalyst under the reaction'conditions. Easily polymerizable materials are more detrimental whenthe process is executed in the vapor phase. Olefins, when present in anyappreciable amount, tend to sludge and-materially shorten th life of thecatalyst. The detrimental meet" a oleflns is illustrated I Table in mmolefin present absent Ia 27. 9 41. 6 Normal pentane 11. 4 i2. 4 Productsof side reactions 60. 7 i6. 0

1 According to a preferred embodiment of themvention, any olefin orother detrimental impurities in the charge stock are removed prior touse by a suitable treatment, such as a treatment with sulfuric acid. Twomethods of treating the charging stock prior to use which are especiallyeffective and advantageous to remove detrimentalimpurities, are by apretreatment with spent catalyst from the process, and by ahydrogenation treatment. A pretreatment of the charging stock in manycases materially increases the life of the isomerization catalyst eventhough the amount of detrimental impurities appears to be quite small. a

The isomerization is, in general; preferably effected with the aid ofthe most active isomerization catalysts such as the aluminum halidesand, in particular, aluminum chloride or aluminum bromide. Although thealuminum halides are, in general, the most practical and preferredcatalysts, such other acid-acting halide catalysts as exert a catalyticinfluence on the isomerizatlon .of hydrocarbons, e. g. the halides ofBe,v Zn, Zr, Nb, Ta, Sb, B, Cd, and Fe, may also, if desired, be

used,'if desired.

While the above-described solid catalysts are 3 about 300' 0., (mm theysubstantially cease to give off water. duce preferred catalysts whencombined with the metal halides, and especially the aluminum halides,other carrier or supporting materials, such as activated charcoal, coke,crushed brick, pumice, porcelain chips, and the like, may alsobepreferred, the catalyst may be employed in other forms, if desired.Thus, for example, the metal halide may be simply suspended in thereaction mixture, or it may be employed in the form of a complex doublecompound with a phenolic, aroniatic, or other compound, such, forinstance, as the compounds of the types known as Gustavson's compounds"(C 1903 II 1113) and the Ansolvo acids" (Ann 455227-253).

Certain catalysts, such as aluminum bromide, may be employed in any of.thesevarious ways, or may, if desired. be employed as a liquid or insolution in the reaction mixture. The reaction employed. Ingeneral. thecatalyst is employed in an amount equal to from about 1 to 20% by weightof the hydrocarbon being treated although larger or smaller amounts canbe used.

The catalysts are preferably employed in th I solid state in anysuitable form such as granules,

powder, or pellets of the desired size, preferably .deposited on ormixed with a suitable solid 'supporting or carrying material.Particularly ef-- fective catalysts are produced when a metal halidecatalyst is supported on or intimately mixed with one of the varioussiliceous and/or aluminous materials of natural or synthetic originwhich contains an appreciable amount of firmly-bound water.

Suitable materialsof'this category are, for example, thenatural-occurring minerals and clays such as pipe clay, bauxite,-fullers earth, bentonite, kaolin, Florida earth, meerschaum, infusorialearth, kieselguhr, diato maceous earth, montmorillonite, the permutites,and the like; the various treated clays andclaylike materials such asTonsil, Celite, Sil-O-Cel.

Terrana, and the like: and artificially. prepared materials such asActivated Alumina, silica gel, the artificial permutites, and the like.These masolution. The hydrogen halide teriais' are preferably heated ina dry atmosphere at a temperature somewhat higher than that at whichthey are to be employed, for instance at mixture may or may not.contain, besides the hydrocarbon to be treated, varying amounts. ofsolvents, inert dilu'ents,'-flxed gases, etc.

The process of the present invention is always executed in the presenceof at least a small amount of free hydrogen halide. It is known that thecatalytic activity of aluminum halides and other Friedel-Craft typecatalysts is greatly in- .creased by the presence of a hydrogen halide.Thus, it is found that the rate of iso'meri'zation of hydrocarbons,using these catalystsds, in; general, increased appreciably by thepresence of a hydrogen halide. The effect of hydrogen halides inisomerization reactions is, however, unusual in that-it is more orlessproportional to the amount present. This is illustrated, forexample,

in the following table showing the results of comparative experiments onthe isomerization of normal pentane in the presence of 10% by weight ofaluminum chloride at 29 C. for 17 hours.

TableIV i Isoparailin Partial pressure of HCl in atmospheres M8 productPercent The hydrogen halides, however, likewise tend to promote crackingand decomposition reactions; especially at, elevated temperatures, andhave,.

therefore, hitherto been employed only in small amounts. Animportant-feature of this invention is that the beneficial eifect oflarge amounts of hydrogen halide can be utilized while cracking" anddecomposition reactions are effectively in hibited. In the preferredembodiment of my invention I, therefore, employ a substantial amount ofa hydrogen halide such, for example, as a par-.

tial pressure of. hydrogen chloride, hydrogen bromide or hydrogenfluoride-of at least oneatmospliere (measured at 20 C.) and, morepreferably, from about three to about, twenty atmospheres. The hydrogenhalide is preferably added directly, in. any convenient manner, as aliquid,- gas, or may; however, be generated in the reaction zone, ifdesired. by in troducing a material which will decompose or react underthe prevailingconditions to form the Although these materials prodesiredhydrogen halide. Suitable materials which may be added for this purposeare, for example, chlorine, bromine, water, organic halides such astertiary butyl chloride, organic hydroxy compounds such as ethanol,inorganic salts containing molecular-bound hydrogen halide such asPbS04.2HCl, CuSO4.2HCl, and the like.

when operating in the vapor phase, the hydrocarbon to be treated, may,for example, be

* bubbled through tertiary butyl chloride or-other volatile, readilydecomposable halide prior to its passage into the reaction chamber- Thecatalytic isomerization, according to the process of the presentinvention, is executed in the presence of a metal which is capable ofreacting with a portion of the hydrogen halide present under thereaction conditions. Examples of such metals which inhibit cracking andother undesirable side reactions are, for instance, aluminum, beryllium,magnesium, calcium, zinc, copper, iron, silver, and the like. Of theavailable metals aluminum is exceptionally eflective and preferred. Thealuminum or other metal employed need not necessarily be pure but may bean alloy such, for instance, as an alloy of aluminum and zinc.

The aluminum or other metal is preferably employed in a state offering alarge surface such as, for instance, in the form of turnings, shavings,filings, flakes or powder. In some cases it is advantageous to activatethe surface of the metal prior or during use. This may be done, forexample, by treating it prior to use with a solution of a salt of a lesselectropositive a metal such as Hg; Cu, U, etc., or in some cases,

by contacting it with a small amount of mercury.

admixture with the isomerization catalyst, since the effectiveness is tosome extent dependent upon the intimacy of the mixture. Thus, aluminumin the form of a powder may be mixed with The metal is preferablyemployed in intimate the isomerization catalyst and the carrier materialprior toforming the mixture into pellets or other suitably shapedpieces, for instance, by pressing. The metal may also, if desired, beincorporated in the catalyst bed or, if the reaction is executed in theliquid phase, suspended in the reaction mixture. y

The amount of metal required to produce the 'optimum results dependsupon the fineness of subdivision of the metal, the. activation of thetions will not be most eflectively inhibited.-

Large, excessive amounts oi. metal effectively inhibit the sidereactions but also tend to inhibit the isomerization to an appreciableextent.

- The amount of metal preferably employed for any given set ofconditions may easily be determined in practice by adding increments ofthe metal until the decomposition reactions are inhibited'to the desiredextent. I

As will be apparent, the metal will react to a greater or lesser extentwith the hydrogen halide present under the reaction conditions to formmetal halides which, especially if the catalytic influence. Care shouldbe taken, .therei'ore, that suilicient metal is added so that there isalways free metal in the reaction zone. When aluminum is employed as themetal and the hydrogen halide concentration is properly adjusted, it ispossible to generate sumcient alu-' minum halide in the reaction zone toeflect the isomerization without the addition of further quantities ofaluminum halide. While this is possible, the results are, in general,not as good as when operating in the presence of added catalyst.

If it is attempted to isomerize the present hydrocarbons with the aid ofa metal halide catalyst, such as an aluminum halide in particular,

in the presence of a hydrogen halide, but without the presence of aninhibiting metal, it is found that at low temperatures the isomerizationtakes place very slowly, generally without excessivedecomposition. Asthe temperature is increased, the isomerization takes place at aamountof catalyst, amount of hydrogen halide,

etc. Since, however, under these strongly inhibited conditions theisomerization is usually somewhat less than can be obtained at lowertemperatures, the process is, in general, preferably executed attemperatures below about 200 C. and most preferably between about 30 C.and about 1 80 C. p p

The present process may be executed at any pressure from about oneatmosphere up to as high as desired. Since the process is, however,usually executed in the presence of at least one atmosphere andpreferably between about three and twenty-atmospheres pressure of ahydrogen halide (measured at 20 C. ),.the pressure usually exceeds threeatmospheres and is often in the neighborhood of 5-50 atmospheres. The.pressure is usually due to the vapor pressure of the hydrocarbon treatedand the hydrogen halide, but may also 'be due to other gases such as Ha,Ha, CO2, and the like.

The process may be advantageously executed inthe liquid phase. Thus, thereaction may be conveniently executed in a suitable continuous reactorof the autoclave type, preferably equipped with suitable heating andagitating means, or the liquid reaction mixture may be circulatedthrough a chamber, reactor, 01' towercontaining the catalyst andmaintained at the desired temperature.

According to a preferred embodiment of the invention the hydrocarbon tobe treated, for example a commercial pentane fraction, is vaporized andthe vapors. along with a suitable quantity of hydrogen halide, passedthrough a bed of the catalyst metal mixture maintained at the desiredtemperature. I

An importantadvantage of the'present process in that in the presence ofeven small airlounts metal employed is aluminum,may also exert a 18 ofaluminum metal the. catalysts 2,265,870 imdergo much less alterationduring the treatment and remain active for a long time. The lowesttemperature at which it is possible to effect the reaction in the vaporphase depends upon the hydrocarbonor mixture of hydrocar-.

bons treated and upon the pressure employed.

The following examples illustrate suitable applications and aspects ofthe process of the in vention and the advantageous results obtainablethereby.

Exmm III 100 grams of a commercial pentane fraction.

containing 91.5% normal pentane and 8.5% isopentane were treated forhours at 40 C.;wlth

- 10 grams of aluminum chloride and 10 grams Decomposition andpolymerization prod uc Y 10.2

' Thus it is seen that although aluminum chloride in the presenceofhydrogen chloride does promote isomerization, in the case of theisomerization of normal pentane, considerable decomposition andpolymerization products are formed, even at 40 C. when the aboveexperianalyses of the products obtained at the several temperaturesarevshown in the following table:'

- -Table V Normal tion and Temperature, 0. Isopentane mane I new p6 oproducts Percent Percent Percent 34,7 04.8 i 0.5 46. 8 52. 6 0. 7 43.4to: 1.: 87.2 57.7 5.1 88.3 03.3 8.4 34.2 55.4 10.4

Exsmna VI 100 gram portions of a commercial pentane fraction containing85.9% normal pentane .and- 14.1% isopentane were treated with 10 gramsofaluminum chloride and 6 grams of aluminum powder in acne liter VzA steelrotating autoclave for five hours at C. under various par-v tialpressures of hydrogen chloride- The percent conversion to isopentane,corresponding to the different pressures of hydrogen chloride used. areshown in the following table:

g Table VI 4 and washing with lye contained:

sirable lay-products is substantially obviated and the conversion ofnormal pentane toisopentane is considerably increased.

I Exsmn: IV 100 grams of normal pentane,'l gram .of aluminum powder, 10gra ns of hydrogen chloride,

and 20 grams of aluminum chloride were charged to a. ViiA steel rotatingautoclave and the mixture reacted for ten hours at 40 C. The reactionproduct, after decanting from the catalyst Thusit is seen that whereas10 grams of aluminumchloridecaused a large amoimt of decomposition, thedecomposition when using 20 grams of aluminum chloride was eflectivelyinhibited by one gram of metallic aluminum.

Exsmru: V

'100 gram portions of a commercial pentane fraction containing 91.5%normal pentane and 8.5% isopentane were reacted in the presence of minumpowder and 10 grams of hydrogen chloride for five hours at various.temperatures. The

Thus it is seen that in the pr sence of 6 grams of powdered aluminum theformation of undeweight of the amount'of. aluminum chloride employed. 1

ment'was repeated under the same conditions, vrassymeiflclinfltmvhem ggm except that 6 grams of aluminum powder were added, the product wasfound to contain:

. a n 4-0 Check or 35 i g. 7 Experiment nmmmt 14 24:4 i? a: *PercentPercent 24 39.4 Isopentane 87.4 34.4 '27 a f i 30.4 Normal pentane ..L02.4 04.8 Decomposition and polymerization 4o Products It is seen fromthis series of experiments that when using 10% of aluminum chloride, 20atmospheres partial pressure of hydrogen chloride.

and a temperature of40 0.. the optimum amount of aluminum powder .isabout 6% by weight of the material treated or about by Emmi: vn-

taining a small amount of isopentane were treated in a one liter VsAsteel rotating autoclave in the presence of=20 .gramsjofaluminumchloride, 10 grams of hydrogen chloride and various amounts ofaluminum powder'for-lo hours" at 40 0. The analyses of the productsobtained,

- corresponding to the different amounts of metal l0 gramsjof aluminumchloride, 6 grams of aluused, are shown in the following table:

Table VI! I Gramsainminumpo der ll tion 31 w an employ Isopentanen-Pentane gown!!!" on products Percent Percent Percent 63.9 35.5 0.653.0 45.0 Ll 54.1 45.3 p 0.6 20.4 73.0 0 37.2 01.6 1.2 29.2 70.8 0

From this series of experiments it is seen that the optimum amount ofaluminum powder uni der these conditions is about 2% of the. amount ofthe aluminum chloride employed.

' Conversion gram portions of commercial pentane con- Exnrrra VIII -Aseries of experiments were made as described in Example VII, except thatthe temperature was increased to 80 C. The analyses of the products areshown inthe following table:

Thus it is seen that whereas at 40 C. 2% oi aluminum powder (based onthe amount of aluminum chloride employed) is sufiicient to effectivelyinhibit the undesirable side reactions when using 10% aluminum chlorideand 10% hydrogen chloride, at 80 C. the optimum amount of aluminumpowder is about At higher temperatures correspondingly larger amounts ofaluminum metal are preferred. a

EXAHPI-i 1x 100 gram portions of a commercial pentane i'ractioncontaining 91.5% normal pentane and 8.5% isopentane were treated in aone liter VzA steel rotating autoclave with 10 grams hydrogen chlorideand 10 and 20 grams powdered aluminum, respectively, for 10 hoursat 40C. The analyses of the products are shown in the fol lowing tablez'Table IX v 10 grams 20' Al powder Al powder Tsopentane cs4 24.: Normalpentane 71. 6 73. 8 Decomposition products 0. 0 2. 0 Percent n-pentaneconverted to isopentane. 7 17. 1

Thus it is seen by comparison with Example III, that theisomerizationmay be more advanta'geously eflfected without the additionof aluminum chloride than with aluminum chloride alone, but lessadvantageously than with aluminum metal plus added aluminum chloride.

Exsuraa X Normal pentane vapors were passed along with hydrogen chloridevapors through a cubic centimeter bed of a catalyst composed oi aluminumchloride (10 parts) and aluminum powder (6 parts), held at a temperatureor 100 C. The isope'ntane content 01' the product varied be-' tween 17.4and.25.4% while the decomposition products varied. from 4.2 to 9.8%.fAluminum chloride deposited on aluminum oxide under comparableconditions, gave a product containing 16.2% isopentane products.

The aboveexamples, which illustrate various aspects of the invention,are not to be considered.

as limiting the invention It is to be understood that modifications willbe readily apparent to 1. In a process for the isomerization orhydrocarbons wherein asaturated hydrocarbon c mtaining at least fivecarbon atoms is contacted with an aluminum chloride isomerizationcatalyst and a hydrogen halide promoter under isomerization conditionsto eflect isomerization as the predominant reaction, the improvementwhich comprises eflecting the isomerization reaction in the presence ofan aluminum chloride catalyst containing sufilcient metallic aluminum toreact with a portion of the. hydrogen halide promoter, wherebyundesirable side reactions are repressed.

2. In a process for the isomerization of hydrocarbons wherein asaturated hydrocarbon containing at least five carbon atoms is contactedwith an aluminum chloride isomerization catalyst and ahydrogen halidepromoter under isomerization conditions to eflect isomerization asthepredominant reaction, the improvement which comprises effecting theisomerization reaction in the presence of an aluminum chlorideisomerization catalyst containing a metal which reactswith a portion ofthe hydrogen halide promoter, whereby undesirable side reactions arerepressed.

3. In a process for the isomerization of hydrocarbons wherein asaturated hydrocarbon containing at least five carbon atoms is contactedwith a Friedel-Craits type metal halide isomerization catalyst and a hyr gen halide promoter under isomerization conditions to efiectisomerization as the predominant reaction, the improve ment whichcomprises effecting the isomerization reaction in the presence ofsufllcient metallic aluminum to react with a portion 01! the hydrogenhalide promoter,whereby undesirable side reactions are repressed.

4. In a process for the isomerization oi hydrocarbons wherein asaturated hydrocarbon .containing at least fivecarbon atoms is contactedwith an-aluminum halide isomerization catalyst and a hydrogen halidepromoter under isomerization conditions to effect isomerization as thepredominant reaction, the improvement which comprises efi'ecting theisomerization reaction in the presence of an aluminum halideisomerization 'catalyst containing a metal which reacts with a portionof the hydrogen halide promoter, whereby undesirable side reactions arerepressed.

5. In a process for the isomerization of hydrocarbons wherein asaturated hydrocarbon con-- taining at least five carbon atomsiscontacted with. a Friedel-Crafts type metal halide isomerizationcatalyst and a hydrogen halide promoter under isomerization conditionsto eflect isomer ization as the predominant reaction, the improvementwhich comprises effecting the isomerization reaction in the presence ofa metal which re acts with a portion of the hydrogen halide protanefromnormal pentane wherein normal penf tans is contacted with aFriedel-Crai'ts type a metal halide isomerization catalyst and a hydro?gen halide promoter under isomerization condi-- tions to efi'ectisomerization as the predominant reaction, the improvement whichcomprises eitecting the isomerizationreaction in the presence of a metalwhich reacts with a portion of the hydrogen halide promoter, wherebyundesirable side reactions are repressed.

7. In a process for the production 01 isopentane 1 from normal'pentan'ewherein normal pentane moter, whereby undesirable side reactions arerepressed. I

6. In a process for the production 01' isopenis contacted witha-Friedel-Crafts type metal' halideisomerization catalyst and a hydrogenof suificient metallic aluminum to react with a portion of the hydrogenhalide promoter, where-- by undesirable side reactions are repressed.

8. In a process for the production of isopentane from normal pentanewherein normal pentane is contacted with an aluminumhalide isomerizationcatalyst and a hydrogen halide promoter under isomerization conditionsto efiect isomeriz ation as the predominant reaction, the improvementwhich comprises efiecting the isomerization reaction in the presence ofan aluminum halide isomerization catalyst containing a metal whichreacts with a portion of the hydrogen halide promoter, wherebyundesirable side reactions are re- 1 pressed.

9. In a process for the production of isopentane from normal pentanewherein normal pentane is contacted with an aluminum chlorideisomerization catalyst and a hydrogen halide promoter underisomerization conditions to efiect isomerization as the predominantreaction, the improvement which comprises effecting the isomerizationreaction in the presence of an aluminum chloride catalyst containingsufiicientr etallic aluminum to react with a portion of the hydro:

gen halide: promoter, whereby undesirable side- 15 reactions arerepressed.

w GEORGE CORNELIS ADRIAAN SCHUI IT.

